The present invention relates to a suspension system for a fifth wheel hitch mounted on a truck tractor for pulling a trailer.
A trailer is connected to a truck tractor at what is termed a fifth wheel hitch. The force transmitted from the tractor to the trailer for pulling the trailer is transmitted through the fifth wheel hitch. Also, a vertical force is applied to the tractor by the trailer through the fifth wheel hitch. In a static condition, the force applied by the trailer to the tractor will be a constant vertical downward force. The magnitude of the constant vertical downward force will depend on the weight of the trailer and the weight of any cargo carried by the trailer.
During the pulling of the trailer by the tractor, the trailer is subjected to uneven pavement, such as pot holes, bumps, etc. The trailer reacts to the uneven pavement as an inertial mass. Such reaction causes a change in the amount of vertical force transmitted from the trailer to the tractor at the fifth wheel hitch. The variation in the vertical force transmitted to the tractor from the trailer due to uneven pavement disturbs the tractor causing poor ride and poor handling conditions. It is desirable to reduce the variation in the vertical force transmitted from the trailer through the fifth wheel hitch to the tractor due to the trailer encountering uneven pavement.